The specimen holder is a component of an electron microscope providing the physical support for specimens under observation. Specimen holders traditionally used for TEMs and STEMs, as well as some modern SEMs, consist of a rod that is comprised of three key regions: the end (300), the barrel (200) and the specimen tip (100) (see, e.g., FIG. 1). In addition to supporting the specimen, the specimen holder provides an interface between the inside of the instrument (i.e., a vacuum environment) and the outside world.
To use the specimen holder, one or more samples are first placed on a specimen support device. The specimen support device is then mechanically fixed in place at the specimen tip, and the specimen holder is inserted into the electron microscope through a load-lock. During insertion, the specimen holder is pushed into the electron microscope until it stops, which results in the specimen tip of the specimen holder being located in the column of the microscope. At this point, the barrel of the specimen holder bridges the space between the inside of the microscope and the outside of the load lock, and the end of the specimen holder is outside the microscope. To maintain an ultra-high vacuum environment inside the electron microscope, flexible o-rings are typically found along the barrel of the specimen holder, and these o-rings seal against the microscope when the specimen holder is inserted. The exact shape and size of the specimen holder varies with the type and manufacturer of the electron microscope, but each holder contains these three key regions.
The specimen holder can also be used to provide stimulus to the specimen, and this stimulus can include temperature, electrical current, electrical voltage, mechanical strain, etc. One type of specimen holder is a semiconductor device. The semiconductor device can be designed to have an array of electrical contact pads on it, and the sample holder can be designed to transfer electrical signals from an external source, through the holder, to the semiconductor device. Existing devices use delicate wires or clips to create the contact between the holder and the device. Further, said devices provide lower density (i.e., less) electrical contacts to the devices, which is disadvantageous when the user wants to perform multiple experiments all on the same device.
The need for high density arrays comes from an increasing demand to perform a wider variety of experiments on a sample within the microscope—a field known as in situ microscopy. As demonstrated in previous filings by the present inventors, semiconductor specimen support devices can be made to interact with the sample by passing current or creating fields across or near a sample. These electrical signals can be used to heat, cool, bias or charge a sample, all while being viewed in real time within the microscope. It is an object of the present invention to increase the number of electrical contacts provided to a sample, thus increasing the number of or type of experiments that can be done on the same device.